Change material of object between multiple scenes
If you can afford to actually make a copy just of the car object, you can have two objects with the same settings but different material. For this you need to switch the material from Data to Object, otherwise it still has the same material for the same mesh.



However, if you can't copy the object you may have to do some python trickery to get it working. Below you'll find a quick test using a scene_update_pre handler function. This is called when the renderer updates each scene, so you can use it to switch colors or do anything else needed. You will have to adjust the handler according to your blend file and material setup.